The invention relates to mail processing systems, and more particularly to mail weighing and postage determination systems.
Mail processing systems typically comprise a feeder assembly that singulates mail items and delivers them to a sorting assembly. Mail items may include, for example, letters, newspapers, magazines, postcards and padded envelopes. The sorting assembly may weigh, scan and sort mail items.
It is desirable for the system to process mail at a high rate of speed. Available systems are capable of sorting mail at speeds of greater than 30,000 mail items per hour. Portions of the mail processing systems, such as scanners and transport assemblies, can readily attain these speeds. A limiting factor in a mail processing system""s speed may be the system""s mail weighing step. The mail weighing step is of particular importance because postage amounts are based on mail item weight.
In conventional mail processing systems, mail items are weighed individually. The weight may then be relayed to a computer that calculates the correct postage and causes it to be applied to the mail item. The weighing step is typically slower than the speed of other mail processing system steps. Each mail item must be moved from the scale before another item may be weighed. This requires a pause which slows the process. Accordingly, there is a need for a weighing system capable of reliably weighing mail items, at a relatively high rate of speed.
When a mail item is introduced onto a scale, it must settle before an accurate weight is determined. This adds to the weighing time. Furthermore, if the mail item has not settled before the weight is determined, an erroneous weight value may be obtained, and therefore, an incorrect postage amount. Therefore, there is a need to account for settling time, and/or rely only on weights obtained after settling is complete.
Weighing errors may also arise because of scale vibration. Such vibration is often caused by motion of other parts of the mail processing system. Accordingly, there is a need to reduce scale vibration caused by other mail processing steps.
Significant time may be lost in a mail processing system if a mail item is inaccurately weighed or otherwise improperly processed. In a conventional system, it may be difficult to determine when an error occurs, and thus stop mail processing in a timely manner. Therefore, a need exists for a mail processing system able to detect weighing errors and cease operation immediately upon detection.
Embodiments of the present invention provide a mail weighing system that can improve the speed of mail processing by weighing mail items in bulk. The present invention can also reduce process time wasted when mail is not weighed accurately. Advantageously, mail items can be weighed more accurately, and therefore, more accurate postage determinations can be made.
Aspects of the invention include a method of processing a plurality of mail items in an automated system. In a first embodiment of the invention, a plurality of mail items enters the system and a record is created for each item. The mail items are then weighed and a determination is made as to whether the weight is a valid mail item weight. If the weight is valid, it is entered on the mail item record. If the weight is not valid, at least a portion of the mail processing system is stopped.
A further embodiment of the invention provides a method of processing mail in which mail may be weighed without isolating each mail item on a scale. The method begins by determining a first scale weight reading which may be of an empty scale or a scale containing mail items or other objects thereon. A mail item is then introduced onto this scale. The mail item weight is determined at one or more times within a time window. The difference between each consecutive scale weight is determined. If a difference between scale weight readings is not equal to zero, the difference is outputted. The mail item weight is then determined by adding all outputted scale weight difference readings. A postage amount then can be calculated based on the mail item weight.
In a further aspect of the invention a time window is set for weighing a mail item. A time window is set between determining the mail item weight and the end of the time window. The mail item is introduced onto a scale and takes time in settling. A determination is made as to whether the scale settles before the time window closes. If the scale does not settle before the time window closes, at least a portion of the mail processing system is stopped. If the scale settles before the time window closes, the mail item weight is determined, and a postage amount can be calculated based on the weight.
Embodiments of the invention also include a mail processing system. The system includes a weighing portion having a plurality of scales to weigh a plurality of mail items. The number of scales is equal to the weighing time per scale, divided by the average time between consecutive mail items entering the mail processing system""s weighing portion, rounded to the next higher number. This allows for mail items to be weighed at the same rate as they are processed in other portions of the system.